audio/coreaudio: Remove a deprecation warning on macOS 12

audio/coreaudio: Remove a deprecation warning on macOS 12

When building on macOS 12 we get:

  audio/coreaudio.c:50:5: error: 'kAudioObjectPropertyElementMaster' is deprecated: first deprecated in macOS 12.0 [-Werror,-Wdeprecated-declarations]
      kAudioObjectPropertyElementMaster
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      kAudioObjectPropertyElementMain
  /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/CoreAudio.framework/Headers/AudioHardwareBase.h:208:5: note: 'kAudioObjectPropertyElementMaster' has been explicitly marked deprecated here
      kAudioObjectPropertyElementMaster API_DEPRECATED_WITH_REPLACEMENT("kAudioObjectPropertyElementMain", macos(10.0, 12.0), ios(2.0, 15.0), watchos(1.0, 8.0), tvos(9.0, 15.0)) = kAudioObjectPropertyElementMain
      ^

Replace by kAudioObjectPropertyElementMain, redefining it to
kAudioObjectPropertyElementMaster if not available.

Suggested-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Suggested-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Suggested-by: Roman Bolshakov <roman@roolebo.dev>
Reviewed-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Tested-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>